var client = (function() {
  //呈现引擎
  var engine = {
    ie: 0,
    gecko: 0,
    webkit: 0,
    khtml: 0,
    opera: 0,

    //完整的版本号
    ver: null
  }
  //浏览器
  var browser = {
    //主要浏览器
    ie: 0,
    firefox: 0,
    safari: 0,
    konq: 0,
    opera: 0,
    chrome: 0,

    //具体的版本号
    ver: null
  }
  //平台、设备和操作系统
  var system = {
    win: false,
    mac: false,
    x11: false,

    //移动设备
    iphone: false,
    ipod: false,
    ipad: false,
    ios: false,
    android: false,
    nokiaN: false,
    winMobile: false,

    //游戏系统
    wii: false,
    ps: false
  }

  //检测呈现引擎和浏览器
  var ua = navigator.userAgent
  if (window.opera) {
    engine.ver = browser.ver = window.opera.version()
    engine.opera = browser.opera = parseFloat(engine.ver)
  } else if (/AppleWebKit\/(\S+)/.test(ua)) {
    engine.ver = RegExp['$1']
    engine.webkit = parseFloat(engine.ver)

    //确定是 Chrome 还是 Safari
    if (/Chrome\/(\S+)/.test(ua)) {
      browser.ver = RegExp['$1']
      browser.chrome = parseFloat(browser.ver)
    } else if (/Version\/(\S+)/.test(ua)) {
      browser.ver = RegExp['$1']
      browser.safari = parseFloat(browser.ver)
    } else {
      //近似地确定版本号
      var safariVersion = 1
      if (engine.webkit < 100) {
        safariVersion = 1
      } else if (engine.webkit < 312) {
        safariVersion = 1.2
      } else if (engine.webkit < 412) {
        safariVersion = 1.3
      } else {
        safariVersion = 2
      }

      browser.safari = browser.ver = safariVersion
    }
  } else if (/KHTML\/(\S+)/.test(ua) || /Konqueror\/([^;]+)/.test(ua)) {
    engine.ver = browser.ver = RegExp['$1']
    engine.khtml = browser.konq = parseFloat(engine.ver)
  } else if (/rv:([^\)]+)\) Gecko\/\d{8}/.test(ua)) {
    engine.ver = RegExp['$1']
    engine.gecko = parseFloat(engine.ver)

    //确定是不是 Firefox
    if (/Firefox\/(\S+)/.test(ua)) {
      browser.ver = RegExp['$1']
      browser.firefox = parseFloat(browser.ver)
    }
  } else if (/MSIE ([^;]+)/.test(ua)) {
    engine.ver = browser.ver = RegExp['$1']
    engine.ie = browser.ie = parseFloat(engine.ver)
  }
  //检测浏览器
  browser.ie = engine.ie
  browser.opera = engine.opera
  //检测平台
  var p = navigator.platform
  system.win = p.indexOf('Win') == 0
  system.mac = p.indexOf('Mac') == 0
  system.x11 = p == 'X11' || p.indexOf('Linux') == 0
  //检测 Windows 操作系统
  if (system.win) {
    if (/Win(?:dows )?([^do]{2})\s?(\d+\.\d+)?/.test(ua)) {
      if (RegExp['$1'] == 'NT') {
        switch (RegExp['$2']) {
          case '5.0':
            system.win = '2000'
            break
          case '5.1':
            system.win = 'XP'
            break
          case '6.0':
            system.win = 'Vista'
            break
          case '6.1':
            system.win = '7'
            break
          default:
            system.win = 'NT'
            break
        }
      } else if (RegExp['$1'] == '9x') {
        system.win = 'ME'
      } else {
        system.win = RegExp['$1']
      }
    }
  }
  //移动设备
  system.iphone = ua.indexOf('iPhone') > -1
  system.ipod = ua.indexOf('iPod') > -1
  system.ipad = ua.indexOf('iPad') > -1
  system.nokiaN = ua.indexOf('NokiaN') > -1
  //windows mobile
  if (system.win == 'CE') {
    system.winMobile = system.win
  } else if (system.win == 'Ph') {
    if (/Windows Phone OS (\d+.\d+)/.test(ua)) {
      system.win = 'Phone'
      system.winMobile = parseFloat(RegExp['$1'])
    }
  }

  //检测 iOS 版本
  if (system.mac && ua.indexOf('Mobile') > -1) {
    if (/CPU (?:iPhone )?OS (\d+_\d+)/.test(ua)) {
      system.ios = parseFloat(RegExp.$1.replace('_', '.'))
    } else {
      system.ios = 2 //不能真正检测出来，所以只能猜测
    }
  }
  //检测 Android 版本
  if (/Android (\d+\.\d+)/.test(ua)) {
    system.android = parseFloat(RegExp.$1)
  }
  //游戏系统
  system.wii = ua.indexOf('Wii') > -1
  system.ps = /playstation/i.test(ua)
  //返回这些对象
  return {
    engine: engine,
    browser: browser,
    system: system
  }
})()

// 计元素 左、上偏移量
function getElementTopLeft(element) {
  var actualLeft = element.offsetLeft
  var actualTop = element.offsetTop
  var current = element.offsetParent

  while (current !== null) {
    actualLeft += current.offsetLeft
    actualTop += current.offsetTop
    current = current.offsetParent
  }

  return {
    top: actualTop,
    left: actualLeft
  }
}

// 确定浏览器视口大小
function getViewport() {
  if (document.compatMode == 'BackCompat') {
    return {
      width: document.body.clientWidth,
      height: document.body.clientHeight
    }
  } else {
    return {
      width: document.documentElement.clientWidth,
      height: document.documentElement.clientHeight
    }
  }
}

// 跨浏览器计算元素相对于视口位置
function getBoundingClientRect(element) {
  var scrollTop = document.documentElement.scrollTop
  var scrollLeft = document.documentElement.scrollLeft

  if (element.getBoundingClientRect) {
    if (typeof arguments.callee.offset != 'number') {
      var temp = document.createElement('div')
      temp.style.cssText = 'position:absolute;left:0;top:0;'
      document.body.appendChild(temp)
      arguments.callee.offset = -temp.getBoundingClientRect().top - scrollTop
      document.body.removeChild(temp)
      temp = null
    }
    var rect = element.getBoundingClientRect()
    var offset = arguments.callee.offset
    return {
      left: rect.left + offset,
      right: rect.right + offset,
      top: rect.top + offset,
      bottom: rect.bottom + offset
    }
  } else {
    var actualTopLeft = getElementTopLeft(element)

    return {
      left: actualTopLeft.left - scrollLeft,
      right: actualTopLeft.left + element.offsetWidth - scrollLeft,
      top: actualTopLeft.top - scrollTop,
      bottom: actualTopLeft.left + element.offsetHeight - scrollTop
    }
  }
}

var EventUtil = {
  addHandler(element, type, handler) {
    if (element.addEventListener) {
      element.addEventListener(type, handler, false)
    } else if (element.attachEvent) {
      element.attachEvent('on' + type, handler)
    } else {
      element['on' + type] = handler
    }
  },
  removeHandler(element, type, handler) {
    if (element.removeEventListener) {
      element.removeEventListener(type, handler, false)
    } else if (element.detachEvent) {
      element.detachEvent('on' + type, handler)
    } else {
      element['on' + type] = null
    }
  },
  getEvent(event) {
    return event ? event : window.event
  },
  getTarget(event) {
    return event.target || event.srcElement
  },
  preventDefault(event) {
    if (event.preventDefault) {
      event.preventDefault()
    } else {
      event.returnValue = false
    }
  },
  stopPropagation(event) {
    if (event.stopPropagation) {
      event.stopPropagation()
    } else {
      event.cancelBubble = true
    }
  },
  getRelateTarget(event) {
    if (event.relateTarget) {
      return event.relatedTarget
    } else if (event.toElement) {
      return event.toElement
    } else if (event.fromElement) {
      return evenet.fromElement
    } else {
      return null
    }
  },
  getButton(event) {
    if (document.implement.implementation.hasFeature('MouseEvents', '2.0')) {
      return event.button
    } else {
      switch (event.button) {
        case 0:
        case 1:
        case 3:
        case 5:
        case 7:
          return 0
        case 2:
        case 6:
          return 2
        case 4:
          return 1
      }
    }
  },
  getWheelDelta(event) {
    if (event.wheelDelta) {
      return client.engine.opera && client.engine.opera < 9.5
        ? -event.wheelDeata
        : event.wheelDelta
    } else {
      return -event.detail * 40
    }
  },
  getCharCode(event) {
    if (typeof event.charCode == 'number') {
      return event.charCode
    } else {
      return event.keyCode
    }
  },

  // 操作粘贴板
  getClipboardText(event) {
    var clipboardData = event.clipboradData || window.clipboardData
    return clipboardData.getData('text')
  },
  setClipboardText(event, value) {
    if (event.clipboardData) {
      return event.clipboardData.setData('text/plain', value)
    } else if (window.clipboardData) {
      return window.clipboardData.setData('text', value)
    }
  }
}
